Cylinder heads

Make

Alfa Romeo

Model

145/146 Factory Service Manual

Year

1994–1999

Section

Engine › Cylinder heads

Technical data and maintenanceCylinder heads

CYLINDER HEADS

Heads

Unit: mm
Diameter of valve guide seat "a"		13.000 ÷ 13.018
Valve guide protrusion "b"		9.3 ÷ 9.5
Minimum permissible height of head after refacing "c"		77.676 ÷ 77.750
Maximum error of flatness of head lower surface		0.03
Valve seat diameter	Intake "d"	40.000 ÷ 40.025
	Exhaust "e"	33.000 ÷ 33.025
Cylinder head heating temperature for fitting valve seats		100° ÷ 120°C

Valve seats

1. Origin profile
2. Profile after maximum reconditioning

Unit: mm
Outside diameter of valve seats	Intake	40.075 ÷ 40.100
	Exhaust	33.075 ÷ 33.100
Reference diameter ØR	Intake	39.0
	Exhaust	31.9
Limit for refacing valve seat upper section "a"		2.9
Limit for refacing valve seat contact area "b"	Intake	1.07 ÷ 1.37
	Exhaust	1.26 ÷ 1.56
Upper valve seat taper "α"		120°
Valve seat contact area taper "β"		90° ÷ 90°30'
Valve seat lower section taper "γ"	Intake	70°
	Exhaust	30°

Valve guides

Unit: mm
Outside diameter of valve guides "a"	13.050 ÷ 13.068
Inside diameter of valve guides "b" (bore)	8.013 ÷ 8.031
Interference between valve guides and seats	0.032 ÷ 0.068

Valves

Unit: mm
Diameter of valve stem "a"	Intake	7.985 ÷ 8.000
	Exhaust	7.968 ÷ 7.983
Diameter of valve mushrooms "b"	Intake	39.700 ÷ 39.990
	Exhaust	33.000 ÷ 33.200
Radial clearance between valve stem and guide	Intake	0.013 ÷ 0.046
	Exhaust	0.030 ÷ 0.063

02 Maintenance